package Problem;

import java.util.Scanner;

//
// Created by ✎﹏ℳ๓独赏☆独醉 on 2024/1/14.
// 
public class 煤球数 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        int sum = 0;
        for (int i = 1; i <= num; i++) {
            int temp = 0;
            for (int j = 1; j <= i; j++) {
                temp+=j;
            }
            sum+=temp;
        }
        System.out.println(sum);
    }
}
